Sifos Technologies PhyView PVA-3000 User manual

PVA-3000 Reference Manual
December 2, 2019 Sifos Technologies
Page 1
Sifos Technologies
PhyView Analyzer
PVA-3000, PVA-3002
Reference Manual
Version 5.1
December 2, 2019
Copyright © 2013-2019 Sifos Technologies
®

PVA-3000 Reference Manual
December 2, 2019 Sifos Technologies
Page 2
Sifos Technologies, Inc.
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The information contained in this manual is the property of Sifos Technologies, Inc., and is furnished for use by recipient
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permitted by such License Agreement, no part of this publication may be reproduced, stored in a retrieval system, or
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Information contained in the user documentation is subject to change without notice and does not represent a
commitment on the part of Sifos Technologies, Inc. Sifos Technologies, Inc. assumes no responsibility or liability for any
errors or inaccuracies that may appear in the user documentation.

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Table of Contents
1. The PhyView Analyzer & Ethernet PHY Testing ............................................................ 7
1.1. PVA-3000 Overview.......................................................................................................................................7
1.1.1. Test Productivity........................................................................................................................................7
1.1.2. Quality Assurance.....................................................................................................................................7
1.1.3. Configurations...........................................................................................................................................7
1.1.4. The PowerSync Analyzer Family of Instruments........................................................................................7
1.2. Ethernet Twisted Pair PHY’s: A Brief History..............................................................................................8
1.2.1. Ethernet Twisted Pair PHY Specification Summary...................................................................................9
1.2.2. Ethernet Symptom Masking.......................................................................................................................9
1.2.3. Traditional PHY Conformance Testing.....................................................................................................10
1.2.4. Time Domain Measurements in PHY Conformance Testing....................................................................10
1.2.5. Packet Testing: Pros and Cons ...............................................................................................................11
1.3. The PhyView Analyzer Metrology ..............................................................................................................12
1.3.1. Link Configurations and Assessments.....................................................................................................12
1.3.2. Transmitter Verification Overview............................................................................................................13
1.3.3. Power Spectral Distortion........................................................................................................................13
1.3.4. Signal-to-Noise Ratio...............................................................................................................................15
1.3.5. Transmit Level Measurement ..................................................................................................................16
1.3.6. Pair Skew Measurement .........................................................................................................................16
1.3.7. Interface Verification –Overview.............................................................................................................16
1.3.8. Bulk Return Loss (Echo) Measurements ................................................................................................16
1.3.9. Bulk Pair-Pair Crosstalk...........................................................................................................................17
1.3.10. Pair Designators in the PhyView Analyzer.............................................................................................18
1.3.11. Receiver Verification Overview..............................................................................................................19
1.3.12. Receiver Testing Metrology...................................................................................................................19
1.3.13. Receiver Testing with Impairments........................................................................................................20
1.3.14. Reference Manual Overview .................................................................................................................21
2. PhyView Analyzer Overview .......................................................................................... 23
2.1. Test Port Interfaces and Configurations ...................................................................................................23
2.2. Test Port Resources...................................................................................................................................24
2.2.1. The PVA-3000 TEST PHY.......................................................................................................................24
2.2.2. PVA-3000 Meters: Overview ...................................................................................................................25
2.2.3. PVA-3000 Meters and Link Rates............................................................................................................25
2.2.4. PVA-3000 Meters: Configuration Maintenance........................................................................................26
2.2.5. Triggered Meters.....................................................................................................................................26
2.2.6. PVA-3000 Meter Calibrations ..................................................................................................................27
2.2.7. PVA-3000 Impairments - Overview..........................................................................................................27
2.2.8. PVA Line Loss and Mismatch Impairments..............................................................................................28
2.2.9. PVA Alien Crosstalk Impairment..............................................................................................................28
2.2.10. PVA Timing Offset and Random Jitter Impairment.................................................................................29
2.2.11. PVA Tx Level and Tx Slew Impairment..................................................................................................30
2.2.12. PVA Rx Gain Control.............................................................................................................................30
2.3. System Software Overview.........................................................................................................................30
2.3.1. PVA Interactive .......................................................................................................................................31
2.3.2. PowerShell PSA Scripting Environment...................................................................................................31
2.3.3. Automated 10/100/1000Base-T Testing: The PHY Performance Test Suite and the pva_veriphy Test....31
2.3.4. PhyView Analyzer Configuration Files.....................................................................................................31
2.3.5. Directory and File Organization –Microsoft Windows..............................................................................33
2.3.6. Directory and File Organization –Linux and Unix...................................................................................34
2.3.7. Tcl/Tk Requirements & Resources ..........................................................................................................34
2.4. (Section Omitted)........................................................................................................................................35
2.5. Network Latency, Host Software, and Host Firewall Considerations......................................................35
2.6. PVA External Channel Impairment Modules .............................................................................................35

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2.7. Technical Data: PVA-3000 ..........................................................................................................................37
2.7.1. Test Port Configurations and Measurements...........................................................................................37
2.7.2. LAN Interface Specifications....................................................................................................................37
2.7.3. Link Partner Transmitter / Incoming Link Integrity Measurements............................................................38
2.7.4. Link Partner Receiver / Link Integrity Measurements...............................................................................38
2.7.5. Impairment Synthesis Specifications .......................................................................................................39
2.7.6. LED Indicators.........................................................................................................................................39
2.7.7. ....................................................................................................................................................................39
2.7.8. Programming and Control........................................................................................................................40
2.7.9. Physical and Environmental ....................................................................................................................40
2.7.10. Certifications .........................................................................................................................................40
3. PVA Interactive Software................................................................................................ 41
3.1. Overview of Menus .....................................................................................................................................41
3.2. Initial PVA Connection................................................................................................................................41
3.3. The PVA Main Menu....................................................................................................................................41
3.4. Loading and Saving DUT Configurations..................................................................................................42
3.5. Navigating PVA Instruments and Test Ports.............................................................................................43
3.6. Port Configuration Menu ............................................................................................................................43
3.6.1. Port Config Menu-Wide Controls.............................................................................................................44
3.6.2. Port Config Actions Sub-Menu ................................................................................................................44
3.6.3. Port Connection Sub-Menu .....................................................................................................................44
3.6.4. Port Impairments Sub-Menu....................................................................................................................44
3.6.5. Active Impairments Sub-Menu.................................................................................................................45
3.7. Configuration Replication ..........................................................................................................................46
3.8. Link Configuration Menu............................................................................................................................46
3.8.1. Link Config Menu-Wide Controls.............................................................................................................47
3.8.2. Link and Gigabit Configuration Sub-Menus..............................................................................................47
3.8.3. Test Signal Sub-Menu.............................................................................................................................48
3.8.4. Test PHY Sub-Menu................................................................................................................................48
3.8.5. Link Config Actions Sub-Menu ................................................................................................................49
3.9. Link Monitor Menu......................................................................................................................................49
3.9.1. Link Monitor Measurements ....................................................................................................................49
3.9.2. Link Partner Assessment.........................................................................................................................51
3.10. Meters Menu...............................................................................................................................................52
3.10.1. Link Speed Configuration ......................................................................................................................52
3.10.2. Pair(s) & Averages Configuration .........................................................................................................52
3.10.3. PSD Frequency Range & Trace Display................................................................................................53
3.10.4. Measurements and Configuration Management ....................................................................................53
3.11. Packets Menu.............................................................................................................................................54
3.11.1. Configuring Packet Addresses...............................................................................................................54
3.11.2. Packet Transmission Configuration and Control....................................................................................54
3.11.3. Packet Reception and Counting ............................................................................................................55
3.11.4. Packet Flow Testing..............................................................................................................................56
3.12. PHY Tests Menu.........................................................................................................................................57
3.12.1. Selecting and Executing Individual Tests...............................................................................................57
3.12.2. Sequencing PHY Performance Tests To A Report.................................................................................58
3.12.3. The DC Unbalance Analysis Application for PSE’s ................................................................................59
3.13. Calibrations Menu......................................................................................................................................59
3.14. Demo Mode.................................................................................................................................................60
3.15. PVA Help Menus.........................................................................................................................................61
3.16. PVA Interactive Examples .........................................................................................................................62
3.16.1. Example 1: Force a DUT on Slot 1, Port 1 to 100Base-T, MDI-X, Full Duplex, with Line Impaired Rx...62
3.16.2. Example 2: Assess Link Stability 1000BaseT DUT in Slave mode, with Line and Offset Impairments...63

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3.16.3. Example 3: Calibrate Test Port for PSD, both 100BaseTX and 1000BaseT..........................................64
3.16.4. Example 4: Measure 4-pair PSD and SNR of Calibration Partner linked at 1000Base-T......................65
3.16.5. Example 5: MeasureWideband Power Loss of Line Loss Impairment given 100BaseTX DUT .............66
3.16.6. Example 6: Establish and Verify Packet Forwarding in a Switch...........................................................67
3.16.7. Example 7 Measure 1000BaseT Packet Loss in a Switch with Impairments Enabled ............................68
3.17. Host Computer and Network Latency Qualification.................................................................................69
4. PowerShell PSA Software .............................................................................................. 71
4.1. TCL and Wish Shells...................................................................................................................................71
4.1.1. Tcl Versus Wish in the PC Windows Environment...................................................................................71
4.2. PSA Connection Dialog..............................................................................................................................71
4.2.1. PowerShell PSA Demo Mode..................................................................................................................72
4.3. PowerShell PSA Command Documentation Conventions .......................................................................73
4.3.1. PowerShell Help Facilities.......................................................................................................................73
4.4. PowerShell PSA Important Global Settings ..............................................................................................73
4.1. Script Editing with Notepad ++ (for Microsoft Windows) .........................................................................73
4.2. PowerShell Connection and Configuration Commands...........................................................................74
4.3. Test Port Connection and Passive Impairment Configuration.................................................................75
4.4. Test Port Active Impairment Configuration...............................................................................................76
4.5. Test Port Trigger Generation......................................................................................................................77
4.6. Test Port PHY Link Configuration..............................................................................................................77
4.7. Test PHY Front-End (PMA) Configuration.................................................................................................79
4.8. DUT Transmitter Measurement Calibrations.............................................................................................80
4.9. DUT Transmitter Measurement Configurations and Queries...................................................................81
4.10. Link Status and DUT Receiver Measurements.........................................................................................85
4.11. PowerShell PSA Test Support Utilities.....................................................................................................87
4.12. PowerShell Calibration Utilities.................................................................................................................89
4.13. PowerShell Multi-Pair Measurement Utilities ...........................................................................................90
4.14. PowerShell Multi-Port Measurement Utilities...........................................................................................91
4.15. PowerShell System & Chassis Commands..............................................................................................92
4.16. PHY Performance Test Suite Commands & Utilities................................................................................93
4.17. pva_veriphy Automated Multi-Port Test Application...............................................................................99
4.18. PowerShell PSA Scripting Examples......................................................................................................100
4.18.1. Example 1: Force a DUT to 100Base-T, MDI-X, Full Duplex, with Line Impaired Rx...........................100
4.18.2. Example 2: Assess Link Stability 1000BaseT DUT in Slave mode, with Line and Offset Impairments.101
4.18.3. Example 3: Calibrate Test Port for PSD, both 100BaseTX and 1000BaseT........................................102
4.18.4. Example 4 Measure 4-pair PSD and SNR of Cal Partner linked 1000Base-T......................................102
4.18.5. Example 5: MeasureWideband Power Loss of Line Loss Impairment given 100BaseTX DUT ...........104
4.18.6. Example 6: Establish and Verify Packet Forwarding in a Switch.........................................................105
4.18.7. Example 7: Measure 1000BaseT Packet Loss in a Switch with Impairments Enabled........................106
5. PHY Performance Test Suite........................................................................................ 109
5.1. Overview....................................................................................................................................................109
5.2. Link Capabilities Test ...............................................................................................................................109
5.3. Transmission and Interface Tests............................................................................................................111
5.3.1. 100BaseTx Transmission Test ..............................................................................................................111
5.3.2. 1000BaseT Transmission Test..............................................................................................................112
5.4. Receiver Tests...........................................................................................................................................112
5.4.1. 10BaseT Receiver Test.........................................................................................................................113
5.4.2. 100Base-TX Receiver Test....................................................................................................................113
5.4.3. 1000BaseT Receiver Test.....................................................................................................................114

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5.5. Standard PHY Performance Test Report.................................................................................................115
5.5.1. Basic Capabilities Test Results..............................................................................................................116
5.5.2. Transmitter and Interface Test Results..................................................................................................116
5.5.3. Receiver Test Results ...........................................................................................................................119
5.5.4. Configuring the Test Report Location ....................................................................................................120
5.5.5. Standard Test Report Built-In Reference Documentation ......................................................................120
5.6. PSE DC Magnetic Unbalance Testing......................................................................................................120
5.6.1. The DC Unbalance Impairment .............................................................................................................121
5.6.2. IEEE 802.3 DC Unbalance Requirements .............................................................................................121
5.6.3. DC Unbalance Analysis with the PhyView Analyzer ..............................................................................122
5.7. PSE DC Magnetic Unbalance Reporting..................................................................................................123
6. Specialized Scripting & Automation with the PVA-3000........................................... 125
6.1. Multiple Port Configuration and Operation .............................................................................................125
6.1.1. Broadcast Test Port Configuration.........................................................................................................125
6.1.2. Event Triggered, Multi-Port Measurements............................................................................................126
6.1.3. Multi-Port Packet Transmission and Analysis ........................................................................................127
...............................................................................................................................................................................127
6.2. Merging the PowerShell PSA API into TCL and Wish Shells..................................................................128
6.2.1. Initial Connection Dialog Control –PowerShell Tcl................................................................................128
6.2.2. Initial Connection Dialog Control –PowerShell Wish (and PSA Interactive)...........................................129
6.2.3. Tcl Version Compatibility.......................................................................................................................129
6.3. Managing PowerShell from External Applications .................................................................................129
6.3.1. API Library ............................................................................................................................................129
6.3.2. TCP Socket Server................................................................................................................................130
6.3.3. Mailbox File Method ..............................................................................................................................131
6.3.4. Batch Mode Methods.............................................................................................................................131
6.4. pva_veriphy Automated Test Application for the PhyView Analyzer ....................................................131
6.4.1. pva_veriphy Tests.................................................................................................................................132
6.4.2. pva_veriphy Reporting...........................................................................................................................133
6.4.3. Managing Test Limits and Link Delay Tolerances in pva_veriphy..........................................................134

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1. The PhyView Analyzer & Ethernet PHY Testing
1.1. PVA-3000 Overview
The PVA-3000 PhyView Analyzer is designed to bridge the wide coverage gap between comprehensive Ethernet
twisted pair PHY compliance testing and rudimentary link verification testing. The PVA-3000 introduces an
innovative, multi-port capability dedicated to 10/100/1000BaseT physical layer characterization under controlled
impairments including line loss, ingress noise, jittered or offset timing, and even Power-over-Ethernet. The PVA-3000
tests Ethernet switches and routers, discrete LAN interfaces, link transmission components, and network service
integrity at any DTE interface.
The key benefits provided by the PVA-3000 are high testing productivity and quality assurance that comes about from
a comprehensive range of measurements and analyses.
1.1.1. Test Productivity
The PhyView Analyzer performs an array of transmitter, interface, and receiver measurements on any
10/100/1000BaseT Ethernet port using a direct RJ-45 plug connection. In combination with the PHY Performance Test
Suite, all testing is fully automated and can be sequenced over 24 DUT ports (or 96 gigabit pairs) with a single click of
a mouse. Comprehensive, colorful, and graphical spreadsheet reports are automatically generated for each device-
under-test (DUT) port tested. There are no special requirements of DUT ports –so long as they can link they can be
fully analyzed by the PhyView Analyzer.
1.1.2. Quality Assurance
For years, engineers and technicians have been constrained by a wide test coverage gap between true IEEE 802.3
physical layer qualification and simple link, or packet flow tests that demonstrate basic functionality with very limited
parametric insight and diagnostic visibility. At one extreme, traditional physical layer testing is very comprehensive
but is also expensive, time consuming –typically one pair at a time, and requires significant expertise. Often, these
tests are not achievable unless DUT’s are placed in special testing modes not available to commercially packaged
10/100/1000BaseT ports.
At the other extreme, link-ups and packet flows can be achieved rather easily and inexpensively. However, this type
testing seldom quantifies any characteristic of performance while relying on “unknowns” testing “unknowns” under
“uncharacterized” conditions.
The PhyView Analyzer fills this wide coverage and productivity gap. Measurements such as transmitter power levels,
transmitter frequency shaping, and signal-to-noise ratio offer quantitative insights into transmission performance
without any more effort than it takes to perform basic link tests and simple packet flows. Interface measurements such
as Return Loss and Crosstalk flag defects that would otherwise serve as hidden impairments. Receivers are
characterized under controlled stresses such as worst case insertion loss, alien crosstalk (ingress noise), timing offsets,
and random jitter. Fully automated stressed receiver tests are performed either with packet flow or link monitor
methods on DUT’s with individual ports as well as multi-port devices such as switches, routers, and repeaters.
1.1.3. Configurations
The PVA-3000 is provided in one of two configurations:
PVA-3000 multi-blade chassis with 12 slots and test capacity of 2 to 24 ports
PVA-3002 two-port, Compact Analyzer
Both configurations offer identical per-test-port features and run from a common host software environment.
The PHY Performance Test Suite is sold as a soft-key enabled option to any PVA-3000 configuration.
1.1.4. The PowerSync Analyzer Family of Instruments
The PhyView Analyzer is a member of the PowerSync Analyzer (PSA) family of test instruments from Sifos
Technologies. The PowerSync Analyzer (PSA-3000) is the industry leader for Power-over-Ethernet (PoE) verification,
analysis, and testing.
The PVA-3000 consists of a PSA-3000 chassis with one or more PVA-3102 test blades. The 12-slot PSA-3000 chassis
can host any combination of PVA-3102 (PhyView Analyzer) and PSA-3202 (PowerSync Analyzer) adding up to 12
test blades. The PVA-3002 consists of a single-slot PSA-3002 controller packaged with a single, 2-port PVA-3102
test blade. From a features and control point of view, the PVA-3002 is identical to a PVA-3000 with a single PVA-
3102 test blade in test slot #1.

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Each member of the PowerSync Analyzer family of instruments shares each of the following features:
Two, fully autonomous micro-controller hosted Test Ports per test blade or per instrument
One instrument controller per instrument
Instrument control over a single 10/100BaseT Ethernet interface
A USB (or older RS-232 Serial) interface exclusively for IP Address configuration and controller
firmware updates
PowerShell PSA: A Tcl/Tk based command console and script automation environment enabling
interactive command line configurations and queries as well as powerful features for automated test
development.
PVA Interactive Graphical User Interface: An instrument-specific software application for
interactive control and testing that sits on top of PowerShell PSA. PVA Interactive for the
PhyView Analyzer is a Tcl/Tk application that provides intuitive access to most PhyView Analyzer
testing resources.
Throughout this manual, the term PSA may be used to refer specifically to the PowerSync Analyzer family and more
specifically to the PSA-3000 chassis.
The PVA-3102 test blade has been engineered to work in all PowerSync Analyzer instrument chassis’. The following
table outlines configuration options and restrictions by chassis type.
Instrument Chassis
Maximum Number of PhyView Analyzer Test Blades
PSA-3000 PowerSync Analyzer for PoE+
12
PSL-3000 Programmable Load for PoE+
12
PSA-1200 PowerSync Analyzer
6 (4 if combined with PSA-1200 test blades)
PSA-1200-PL Programmable Load
6 (4 if combined with PSA-1200-PL test blades)
1.2. Ethernet Twisted Pair PHY’s: A Brief History
Historically, Ethernet twisted pair physical layer (PHY) technology has evolved from simple bi-level digital pulse
signaling (e.g. 10BaseT) to more complex, higher density, wider bandwidth encoding schemes that depend upon
sophisticated digital processing technologies to both generate and recover digital traffic (e.g. 1000BaseT). The “Base”
terminology refers to the fact that Ethernet twisted pair PHY’s are baseband signals rather than modulated carriers that
are typically found in broadband network connections.
Under IEEE 802.3, strict rules regarding backward
compatibility and technology coexistence have assured smooth
and seamless transitions to newer and faster networking
technologies. The introduction of Auto-Negotiation with
100BaseTx enabled link partners to determine technology
compatibility so that links start up with the highest possible
performance level. Auto-Negotiation has since evolved to
resolve numerous link features between link partners.
On the cabling side, EIA/TIA Category 3 structured cabling
created the electrical conduit for 10BaseT. This was a low cost
transmission medium with capability to connect link partners up
to 100 meters apart. Category 3 cabling offered at least two
twisted pairs to support transmission in each direction. Primary RF characteristics included insertion loss (s21), return
loss (s11), and crosstalk. These parameters were verified out to 16MHz. 10BaseT’s transmission spectrum is tightly
spread around 10MHz given the Manchester coding of digital data.
Category 5 structured cabling generally included 4 pairs with parametric verification through 100MHz. This
performance enabled a 100BaseTx technology that was largely borrowed from FDDI (TP-PMD). The 100BaseT
coding scheme, MLT-3, spread the RF bandwidth of a transmitted signal well beyond 50 MHz, thus requiring the
added transmission bandwidth in order to support the 100 meter link length objective. Like 10BaseT, 100BaseTx only
required 2 pairs, one for transmission in either direction. This left two “spare pairs” in each cabling path.
While 100BaseTx extended both frequency spectra and information density, 1000BaseT took advantage of the four pair
cabling structure and then combined that with a duplex transmission scheme that simultaneously transmits signals in
both directions on the same twisted pair. Coupling that with higher density coding schemes, data bandwidth increased
an order of magnitude with very little spectral impact. On the cabling side, Category 5e was introduced to slightly
1990 1995
10BaseT
100BaseTx
1999
1000BaseT
10GBaseT
2006
E.E.E.
2010
PoE
2003
PoE+
2009
Cat 3
Cat 5
Cat 5e
Cat 6
TIA/EIA 568
IEEE 802.3
1990 1995
10BaseT
100BaseTx
1999
1000BaseT
10GBaseT
2006
E.E.E.
2010
PoE
2003
PoE+
2009
Cat 3
Cat 5
Cat 5e
Cat 6
TIA/EIA 568
IEEE 802.3
Figure 1.1 IEEE 802.3 & TIA/EIA 568 Timeline

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improve on attenuation (insertion loss), return loss, and crosstalk specifications. In addition, more crosstalk
measurements were defined owing to added sensitivity of 1000BaseT to crosstalk.
10GbaseT was introduced more recently and is largely utilized as a backbone technology at this time. This manual
will focus on 10/100/1000BaseT, the predominant Ethernet edge access technologies that are addressed by the
PhyView Analyzer.
1.2.1. Ethernet Twisted Pair PHY Specification Summary
The following table briefly summarizes a few of the more important specifications related to the 10BaseT, 100BaseTx,
and 1000BaseT physical layers.
Characteristic
10BaseT
IEEE 802.3 Clause 14
100BaseTx
IEEE 802.3 Clause 25
1000BaseT
IEEE 802.3 Clause 40
Transmission Pairs
1 (unidirectional)
1 (unidirectional)
4 (bi-directional)
Signal Coding
Manchester
MLT-3 (tri-level)
PAM-5 (5-level)
Signal Amplitude
2.5 Vpp
2 Vpp
2 Vpp
Amplitude Band
+ 0.3 Vpp
+ 0.1 Vpp
+ 10.7%
Symbol Rate (Baud)
10 MHz + .01%
125 MHz + .005%
125 MHz + .01%
Symbol Density
1 Bit
1 Bit
8 Bits
Edge Rate Strategy
Manchester, 1 edge / bit
Randomizer
Randomizers
Edge Slew Rate
Mask Fit
(typical 5 nsec)
4 + 1 nsec
Mask Fit
(typical 3.6 nsec)
PHY Layer Error
Detection
None
4b/5b Code
Trellis
Forward Error Correction
None
None
Trellis
Differential Impedance
100+~20
100+~16< 30MHz
100+64,-40@
60MHz
100+~17< 40MHz
100+97,-50@
100MHz
Interface Return Loss
< ~ -20 dB
<~ -21.5 dB < 30MHz
<~ -12 dB > 60MHz
<~ -21.5 dB < 40MHz
<~ -9.5 dB @ 100MHz
Loss Tolerance
-11.5 dB @ 10MHz
-24 dB @ 100 MHz
-24 dB @ 100 MHz
Mismatch Tolerance
+15 @ < -15 dB R.L.
-15 dB R.L. to 20MHz
-8 dB R.L @ 100MHz
-15 dB R.L. to 20MHz
-8 dB R.L @ 100MHz
NEXT Crosstalk
Tolerance
-26 dB @ 10MHz
-27.1 dB @ 100MHz
-27.1 dB @ 100MHz
Noise Tolerance
264 mVpk
(below 15MHz)
40mVpp
(below 100MHz)
40mVpp
(below 100MHz)
Jitter Tolerance
7 nsec Pk-Pk
1.4 nsec Pk-Pk
1.4 nsec Pk-Pk, total
0.3 nsec Pk-Pk > 5KHz
Pair Delay Skew
Not Applicable
Not Applicable
50 nsec (to 100MHz)
Bit Error Target
10-8
10-8
10-10
1.2.2. Ethernet Symptom Masking
Ethernet links are universally designed to recognize packet transmission problems both in the Physical and in the MAC
layer, and when encountering a problem, to drop or discard the erred packet or packet segment. At the physical layer,
packet errors appear as defective preambles (or carrier markers) meaning packets that don’t properly start or complete.
In 100BaseT, coding violations are used as an indication of a flawed transmission. In 1000BaseT, sophisticated digital
signal processing can both recognize transmission errors and attempt to correct them before packet data reaches the
MAC layer.
In the MAC layer, CRC checking determines if there is a probable data corruption in the packet (or the CRC code). If
corruption is discovered, the packet is dropped.
Many Ethernet ports have intelligence to monitor link performance and make decisions to drop link and re-link, and in
certain cases, to force a fall-back into a lower rate in order to get better immunity from link impairments. For
example, a link that starts out at 1000BaseT may eventually drop down to 100BaseT to overcome those impairments.

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10
On the Internet level, the majority of traffic is governed by a transport layer, most commonly TCP, that has intelligence
to know when packets are missing because they were dropped in some link along the network path. TCP can then
communicate to the original sender that certain packets need to be re-transmitted, thus giving them all a second chance
to traverse the network path.
The bottom line is that it is difficult for a user or observer to know when an Ethernet link gets into trouble unless the
problem is so severe that the link is essentially dead. Problems in physical layer communication can be concealed by
an array of self-healing behaviors both in the link and in the network levels.
1.2.3. Traditional PHY Conformance Testing
To some degree, IEEE 802.3 specifications have taken ownership for defining the types of tests and test methods that
should be applied to verify conformance to each physical layer standard. This is particularly true of 10BaseT and
1000BaseT. 100BaseTx was largely imported from the FDDI TP-PMD (ANSI X3:263 1995) and did not incorporate
as much in the way of testing details.
Much of the focus on testing in these documents related to measurements of PHY transmitter characteristics. This is
not surprising because those are far easier to measure than are PHY receiver characteristics. Common PHY
transmitter parameters that appear throughout these specifications include:
Signal Amplitude (min & max)
Transition Slew Rate or Time (min & max)
Signal Symmetry in Amplitude and/or Time (min)
Overshoot & Droop (max)
Edge Jitter (max)
Return Loss and/or Differential Impedance
Receiver testing, when described, is usually limited to Bit Error Rate (BER, or Packet Error Rate, PER) checks. Each
802.3 PHY specification does clearly spell out the types of channel impairments that those physical layers must assume
to exist, meaning that in theory, receiver testing and qualification must be done using representative worst case channel
impairments. However, the actual testing methods and measurements are loosely defined. Similarly, the 802.3
specifications give wide design discretion to topics such as receiver error detection and indication criteria.
1.2.4. Time Domain Measurements in PHY Conformance Testing
Originally, the baseband nature of 10BaseT signals meant that time domain analysis using oscilloscopes was the natural
approach to qualifying transmitted signal integrity to the standard. Most of the above listed transmitter parameters (see
Section 1.2.3) were a good fit with time domain analysis. With the advent of digital scopes, pulse masks could readily
be defined and applied to captured waveforms. Both IEEE 802.3 clause 14 (10BaseT) and clause 40 (1000BaseT)
define test procedures that include a detailed pulse mask.
The only inconvenience in testing twisted pair Ethernet signals with an oscilloscope was that typical scope interfaces
are either 50or 1Mcoaxial while each Ethernet twisted pair was a balanced 100channel. This problem could
readily be resolved with a matching transformer (or balun) that would convert balanced 100to coaxial 50, the only
limitation being that the balun now became a part of the device-under-test.
An alternative interface method was to take each conductor of the twisted pair and route them as center (signal)
conductors to a 2-channel oscilloscope whereby the signal analyzed would be the difference between the two channel
input. This way, the 50inputs could combine to a total 100termination on the twisted pair, though the pair would
no longer be electrically isolated. A third alternative would be to
terminate the twisted pair in a nominal 100load, then probe the
load with a high impedance, high bandwidth differential (active)
probe. This approach keeps the twisted pair isolated but adds cost
and possible calibration of the active differential probe.
The good news about interfacing to the original 10BaseT
transmitter was that there was only a single pair to ever be
concerned with on any given PHY interface. This changed when
auto-sensing MDI/MDI-X was introduce whereby a 10/100BaseT
PHY would have to be able to transmit on either of two pairs
meaning in effect that there were two transmitters that needed to
be tested. 1000BaseT then complicated this further since all 4
pairs possess transmitters meaning that more elaborate fixturing
was required with more manual connection interventions to
perform measurements across the 4 pairs(see Figure 1.2). This
Figure 1.2 Ethernet PHY Test Fixtures

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increased both the equipment and labor costs associated with testing.
A second dilemma associated with traditional transmitter testing came along with 100BaseTx. Most 100BaseTx
PHY’s were actually 10/100BaseT and used auto-negotiation with a link partner to activate a 100BaseT transmission.
When a transmitter pair is connected to a test instrument, there is no link partner and therefore, there is no 100BaseTx
transmitted signaling. This meant that the Ethernet port-under-test either needed some special test mode to activate a
100BaseT transmission, or it needed to start from a linked state with a 100BaseT link partner, then have the transmit
pair separately disconnected so it could get routed to the test instrument. IEEE 802.3 did not define any special test
mode registers so in many cases, especially when testing
finished product, the only option was the latter scheme.
1000BaseT made this even more difficult. When linked,
each pair simultaneously transmits baseband signaling in
both directions, using local hybrid cancellation on each
pair end to sort received signal from transmitted signal.
Additionally, PAM5 signaling is digitally filtered, or pre-
distorted, in order to shape it to the 100BaseT spectra.
So what shows up on each twisted pair is unintelligible.
IEEE 802.3 clause 40 addressed this be defining standard
test signals, standard registers to activate those test
signals, and standard methods for testing those test
signals (see Figure 1.3). This assured that PHY
transmission measurements would be unavailable given
typical finished product.
1.2.5. Packet Testing: Pros and Cons
Given the complexity, cost, and expertise requirements of traditional PHY conformance testing, it is no surprise that
this type testing is done only in design verification, or at a very low sample rate basis, or in a test services setting such
as UNH-IOL. Higher volume testing required a much simpler method and in many cases, that method was packet flow
testing. In fact, many engineers and technicians equate packet flow testing with physical layer testing even though
packet flow testing is purely functional in nature and does not directly measure any physical layer parameters.
Packet flow testing is attractive because it is easy and often low cost. Since Ethernet links universally discard defective
packets, the core requirement is a device that can transmit, receive and count Ethernet packets. Commercial packet
analyzers from manufacturers such as Spirent and Ixia have been widely deployed for years to help with Ethernet
interface and protocol testing. Lower cost, software-based solutions and even Ethernet switches with modified
firmware can serve the purpose of a packet generator / counter.
As a method for evaluating the physical layer, packet flow testing is in truth quite limited in utility and defect coverage
for several reasons:
Limitation #1: It is inherently difficult to resolve packet loss to defects in a transmitter versus a receiver. If two
unknown ports are linked and packets drop in one or both directions, there is no information to suggest whether this is
a transmission problem or a receiver problem. On the other hand, if a known good port is connected to an unknown
port and packets are pinged (meaning the port–under-test has a full protocol stack including ICMP available), any
packet loss is still ambiguous as to whether the unknown port failed to receive them properly or corrupted the
transmission back. This limitation can be partially overcome by accepting Limitation #2.
Limitation #2: The device under test must be a hub,
switch, router, or repeater with 2 or more ports, one of
which is a known good port. Many of the twisted pair
Ethernet ports ever produced are in fact multi-port
devices that can bridge traffic between ports. This allows
known good (or instrument grade) ports to be connected
to the known good port and to any other unknown port
so that the direction of packet loss on the unknown port
should point to a transmission versus receiver problem.
Limitation #3: The degree of bit errors in a link may
provide hints to the severity of a problem but does not
shed any light on the nature of the problem. Figure 1.4
depicts the types of relationships found when comparing
Bit Error Rate (BER) measurements to various physical
impairments or defects. From this figure, it is apparent
that bit errors typically do not appear until the degree of
Figure 1.3 Specialized Transmitter Test Signals
Figure 1.4 BER versus Physical Impairment

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Physical Impairment crosses some threshold level that will depend on the type of defect or impairment. At that point,
the rate of errors will increase at some slope that is also dependent upon the type of impairment involved. As the
graph suggests, a transmit jitter problem may cause a very steep slope from zero to high Bit Error Rate while reduction
in signal power (or higher channel loss) may have a much more gradual impact. Summarizing, knowledge of Bit Error
Rate does not point to the nature of a defect nor does it really describe the magnitude of an impairment.
Limitation #4: Packet flow does not directly measure
Bit Error Rate. There is a statistical relationship
between packet loss and BER and the effect of that
relationship, as described in Figure 1.5, is to
dramatically sharpen, or increase the slope when Packet
Loss is related to Physical Impairment level. Smaller
packets help soften this relationship a bit, however
Ethernet restricts the minimum packet size to 64 bytes
including packet overhead. This translates to 512 bits
for 10BaseT and to 640 bits for 100BaseTx and
1000BaseT owing to coding overheads. The BER
resolution problem is worsened by 1000BaseT where a
degree of forward error correction built into the physical
layer will hide lower bit error levels by reconstructing
partially damaged packets. This in effect increases the
impairment threshold (see Figure 1.4) and sharpens the
slope relating each Physical Impairment to Packet Loss.
Limitation #5: When performing receiver testing, unless the degree of Physical Impairment is carefully manipulated,
it is hard to know whether the Ethernet port-under-test is capable of tolerating IEEE 802.3 specified maximum channel
impairment levels. Measuring zero Packet Loss at zero impairment provides no insight to this capability and therefore
represents minimal defect coverage. On the other hand, if a receiver is exposed to specified maximum channel
impairments of various types and Packet Loss is zero, then it can be determined that the receiver is indeed immune to
the worst-case types of channel impairments it can expect to encounter while in service.
Summarizing, packet flow testing has thrived because it is convenient, low cost, and because the traditional PHY
compliance tests are both expensive and laborious. The PhyView Analyzer was developed to provide much of the
direct physical layer test coverage associated with traditional PHY compliance tests while providing all of the
convenience of a fully automated packet flow test.
1.3. The PhyView Analyzer Metrology
The PhyView Analyzer is designed to make “pure” physical layer measurements. These measurements are made while
linked to an 10/100/1000BaseT port-under-test. Connections are made using high grade RJ-45 cables and plugs so
there is no need of any special fixturing or probing as is common with traditional physical layer test methods.
PhyView measurements and test capabilities can be classified into four different topics:
1. Link Configurations & Assessments: Basic analysis of port-under-test link capabilities and link status
2. Transmission Measurements: Direct measurements of the port-under-test transmitter function
3. Interface Measurements: Evaluation of electrical interface parameters
4. Receiver Tests: Assessments of port-under-test receiver performance characteristics
Each of these areas will be addressed in the following paragraphs.
1.3.1. Link Configurations and Assessments
Link configuration and assessment is the basic ability to determine link state and link configuration, and to control link
configuration. Since link-up and link configuration is essential to all other PhyView Analyzer measurements, the
instrument must have these capabilities. Link configuration features are presented in the following table.
Link Configuration
Options
Description
Link Rate
Auto, 10, 100, 1000, 10/100
Forces specified or at auto-negotiated rate
Connection Mode
Auto, MDI, MDI-X
Forces specified or link determined connection mode
Duplex
Auto, Half, Full
Forces specified or auto-negotiated duplex mode
Gigabit Mode
Auto, Master, Slave
Forces specified or auto-negotiated 1000BaseT gigabit
timing mode
Figure 1.5 Packet Error Rate vs Bit Error Rate
Bit Error Rate
Packet Error Rate
Large Packets
Small Packets
No FEC
FEC
No FEC
FEC
PER=1-(1-BER)Bits/Pkt
Bit Error Rate
Packet Error Rate
Large Packets
Small Packets
No FEC
FEC
No FEC
FEC
PER=1-(1-BER)Bits/Pkt

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Link assessment includes two specific capabilities: Link Monitor and Link Partner assessment.
The Link Monitor reports current link status and link-up parameters such as link rate, duplex, connection mode, and
gigabit mode (1000BaseT only). This can be sampled at any time. The Link Monitor can also be configured to
perform automatic sampling and link status counts over a user-specified period of time. This resource is a key
component to the Receiver Tests topic presented in Section 1.3.12 below.
The Link Partner measurement captures and reports the auto-negotiation and auto-MDI characteristics of a
10/100/1000BaseT port-under-test. This resource is important in qualify which automated tests can be run from the
PhyView PHY Performance Test Suite that is the topic of Section 5.
1.3.2. Transmitter Verification Overview
The PhyView Analyzer will make transmitter measurements while linked using either 100BaseTx or 1000BaseT.
While there are no direct transmitter measurements available for 10BaseT in the PhyView Analyzer, given the
simplicity of a 10BaseT transmission, there are not many possible fault modes that would adversely affect 10BaseT and
not affect 100BaseTx or 1000BaseT. The following PhyView Analyzer measurements assess transmitter performance:
Power Spectral Distortion
Signal-Noise Ratio
Transmission Level
Pair Skew
1.3.3. Power Spectral Distortion
Power Spectral Distortion (PSD) is a measurement of the spectral power characteristics of a 100/1000BaseT
transmitter normalized to a nominal, undistorted 100BaseTx or 1000BaseT transmission spectrum. Figure 1.6
graphically depicts both 100BaseTx and
1000BaseT transmission spectra with and
without packet flow. These spectra have been
adjusted to align peak power levels to 0 dB so
that relative power loss as a function of
frequency is readily visible.
Looking at these spectra, it can readily be
observed that the distribution of power over
frequency is very much tilted to the lower
frequencies. This is critical to how these
technologies overcome the insertion loss of
100M cable channels. Secondly, it is clear
that these spectra are largely not impacted by
packet flow. This is critical to assuring that
IDLE links remain linked with no loss of
receiver synchronization.
The 100BaseTx spectrum shows a distinct
peak in the 16 MHz range, then rolls off to –20 dB by 90 MHz. This characteristic peak relates to a statistical behavior
of the MLT-3 encoding used in 100BaseT. MLT-3 is designed to reduce spectral bandwidth to below 30 MHz.
The PAM5 encoding of 1000BaseT would not naturally produce the band limiting behavior of 100BaseT. So
1000BaseT applies a digital averaging, or low pass filter to roll off the spectrum to roughly match that of 100BaseT.
This protects against high RF emissions and crosstalk that would otherwise result given unshielded twisted pair
transmission media. The pre-distortion filter can then be corrected by the 1000BaseT receiver that knows this exact
filter function. High speed digital signal processing (DSP) is essential in 1000BaseT PHY’s.
The PSD measurement recovers the spectral shape of a transmitted signal, then compares that shape to a nominal, or
idealized spectral shape that depends on the link rate, 100BaseTx or 1000BaseT. This means that the ideal PSD
measurement would be a flat 0dB from low frequency to high frequency. Looking at Figure 1.7, the NOMINAL PSD
trace represents the ideal PSD measurement result.
Many impairments that distort a transmitter signal in the time domain will produce a different type of distortion in the
frequency domain. Figure 1.7 diagrams a number of important distortion types and the expected PSD response to those
impairments. These impairments include:
Figure 1.6 100BaseTx and 1000BaseT Transmission Spectra
Ethernet 100/1000BaseT Spectra
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
010 20 30 40 50 60 70 80 90 100
Frequency MHz
dBc
1000BaseT IDLE
1000BaseT Packet Flow
100BaseTx Packet Flow
100BaseTx IDLE
Ethernet 100/1000BaseT Spectra
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
010 20 30 40 50 60 70 80 90 100
Frequency MHz
dBc
1000BaseT IDLE
1000BaseT Packet Flow
100BaseTx Packet Flow
100BaseTx IDLE

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Low (or High)Output Level: A
low output level as shown Figure
1.8a would equate to a LOW
OUTPUT LEVEL trace in a PSD
measurement (see Figure 1.7).
PSD will be below 0 dB,
especially at the lower frequencies
where most of the spectral energy
exists. Similarly, high output
level would correspond to a
higher PSD in the low frequency
bands. Lower frequency PSD
values are approximately related
to voltage using the relationship
20*LOG(Vp-p/Vp-p_nom)
where Vp-p is actual peak-peak
voltage measurement and Vp-
p_nom is the ideal peak-peak
voltage, e.g. 2Vpp for 100BaseTx.
Assuming for the moment that
PSD at 2 MHz is linearly related
to Vp-p, a 2 MHz 1000BaseT PSD that measures –1.4 dB at 2 MHz would equate to 2Vpp * 10(-1.4 / 20) = 1.7Vpp.
(Note: The 802.3 standard would expect a minimum of 1.79Vpp for 1000BaseT.)
Low (or High) Slew Rate: Slew rate, or Rise/Fall time, tends to affect 100BaseTx and 1000BaseT signals in the
frequency range above 65 MHz with most of the impact observable above 75 MHz. This means a nominal power
signal with low slew rate (see Figure 1.8c) will approximate 0 dB until the upper frequencies where it will decline.
Both a LOW SLEW rate and a HIGH SLEW rate are depicted in Figure 1.7. Relating the low slew rate to the Ethernet
transmission spectra in Figure 1.6, the higher frequencies would roll off even faster. Low slew rate can be especially
harmful in a 100M link where attenuation of higher frequencies is already a challenge to the link integrity. Conversely,
high slew rate will be detrimental in very short links and will lead to RF emissions
problems.
Excess Droop: Droop in any twisted pair baseband transmission (see Figure 1.8b)
typically comes about because a transformer is removing very low frequencies from the
transmitted signal. Transformers are band limited devices that work over a min-max
frequency range. Because PSD can assess frequency response as low as 20KHz, it is able
to discern EXCESS DROOP (see Figure 1.7) that might typically affect frequencies
below 100KHz. In 100BaseT, droop can be directly compared to baseline wander, that is,
the inability of the transmitted signal to hold a steady voltage for a longer period of time
given an all zero’s encoded data pattern. For example, 100KHz would correspond to
10sec, 1,250 symbol periods, or a data pattern of 125 bytes. Power-over-Ethernet can
worsen droop if the delivery of DC current is not evenly split across both conductors of a
twisted pair. This impairment, referred to as DC Unbalance, causes saturation in the
transformer which in turns clips off low frequency response.
Over Filtering: Most 10/100/1000BaseT interfaces use transformer magnetics not only
for isolation but also for EMI and common mode suppression. This requires a low-pass
filtering effect that should nominally roll off above 100MHz. If this filtering cuts off at
lower frequencies like 30 –50 MHz, then PSD will naturally pick this effect up as a
spectral distortion. This is shown in Figure 1.7 as OVER EMI FILTERED.
The PHY Performance Test Suite (see Section 5) takes advantage of relationships
between PSD measurements and certain time-domain measurements in order to predict
parameters such as Vpp (100/1000BaseT), Rise/Fall Time (100BaseT), and Template
Fit (1000BaseT). Those relationships start with theoretical underpinnings including the
topics of these paragraphs, and then add in a body of empirical correlation experience in
order to tighten the predictive accuracy of those critical 802.3 conformance parameters.
PSD is a calibrated measurement so that effects of cabling, connectors, and even test receivers are properly
compensated. Fully automated calibrations requiring no external calibration standards simplify the task of periodic
calibration. PSD can be readily used to measure insertion loss across link components including cabling, connectors,
and patch panels. PSD is also useful for assessing signal integrity at any service point outlet.
Figure 1.8 Impairments in
the Time Domain
Droop
Fast Slew
Slow Slew
Level (Vpp)
(a)
(b)
(c)
(d)
Droop
Fast Slew
Slow Slew
Level (Vpp)
Droop
Fast Slew
Slow Slew
Level (Vpp)
(a)
(b)
(c)
(d)
Figure 1.7 PSD Responses to Various Impairments
Power Spectral Density Impairment Responses
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
010 20 30 40 50 60 70 80 90 100
Frequency MHz
dBc
LOW OUTPUT LEVEL
OVER EMI FILTERED
EXCESS DROOP
LOW SLEW
NOMINAL PSD
HIGH SLEW
Power Spectral Density Impairment Responses
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
010 20 30 40 50 60 70 80 90 100
Frequency MHz
dBc
LOW OUTPUT LEVEL
OVER EMI FILTERED
EXCESS DROOP
LOW SLEW
NOMINAL PSD
HIGH SLEW

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1.3.4. Signal-to-Noise Ratio
Signal-Noise Ratio (SNR) is a measure of residual distortion on a transmitted signal. Residual distortion refers to non-
correctable distortions that occur either because of imperfections in a transmitter or because of problems in a link.
Examples of non-correctable distortion include amplitude noise (or alien crosstalk), phase noise (or severe jitter),
clipping, signal compression (or non-linear gain/loss), and severe inter-symbol interference (ISI) that would occur
given non-linear or notch-like filtering.
Because residual distortion is not correctable, it will for certain adversely affect bit error rate and packet flow in a
receiver. SNR is reported in units of dB, that is, the power of the signal in ratio to the power of non-ideal or distortion
components. 36 dB SNR would mean that the ratio between true signal power and distortion components is 10(36/10) =
3981. (Note: SNR = 10*LOG[PSIGNAL / PNOISE]).
Modern, DSP-based twisted pair PHY receivers are
designed to correct for predictable distortions
including the spectral shaping done in 1000BaseT
and the effects of insertion loss and linear phase
shifting that are characteristic of transmission
media, namely cabling. The PSD measurement
discussed earlier in Section 1.3.3 is designed to be
sensitive these types of impairments or distortions
and will be affected by both “correctable” and
certain residual distortions. To the extent that a
receiver successfully compensates the predictable
distortions, the bit error rate, and ultimately packet
flow, is unaffected by the presence of those
distortions.
One special case of residual impairment is jitter.
While jitter is random, it is to a certain extent, correctable. Receivers are designed to acquire signal timing from the
received signal and thus have some ability to track out, or nullify, randomly varying signal timing. That ability is very
much receiver implementation dependent and will have limitations both in jitter magnitude and jitter rate. Lower
magnitude and lower rate jitter is easily tracked out while high rate (or high frequency) jitter may easily flow through
the receiver and turn up as residual noise. This is why the 1000BaseT standard places a 5KHz bandwidth on the
specification of peak-peak jitter.
In 1000BaseT, receivers have to deal with a special form of quasi-random noise in the form of echoed transmitted
signals and local crosstalk from adjacent transmitting pairs. 1000BaseT receivers are designed to use matched filters
to remove these quasi-random interferers, however, to the
extent that those filters are not perfect or that the hybrid echo
cancellation is not perfect, those interfering signals will show
up as residual noise and affect the bit error rate. While the
PhyView Analyzer as a measuring instrument compensates for
this internal error, this effect also places an upper bound on the
maximum SNR (36 dB) that the meter can report.
The relationship between SNR, Bit Error Rate, and Packet Flow
will generally be design implementation dependent. Figure
1.10 diagrams this using numbers that are realistic but show the
spread of potential performance. From this diagram, it is
evident that 100BaseTx is more tolerant of lower SNR than
1000BaseT in general. It is also evident that SNR in the 30’s
will seldom result in any packet loss at any receiver while SNR
in the low 20’s is a problem in many implementations for
1000BaseT and in the mid-teens will likely be a problem for
100BaseTx on most implementations.
Finally, it should be noted that low transmit signal amplitude will adversely impact measured SNR. This relationship
is essentially in the definition of SNR since lower signal power means that the ratio of signal power to ambient noise
power must decline. This fact should be considered when creating impaired receiver tests as will be discussed
elsewhere in this manual. It also means that SNR measurements can be artificially reduced simply by adding fixed loss
in line with a transmitter-under-test.
Jitter,
Severe ISI
Crosstalk/Noise
Clipping/Compression
Severe ISI
Alien Crosstalk
Severe ISI
Jitter,
Severe ISI
Crosstalk/Noise
Clipping/Compression
Severe ISI
Alien Crosstalk
Severe ISI
Figure 1.9 Sources of Residual Distortion
Figure 1.10
SNR vs Packet Flow

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1.3.5. Transmit Level Measurement
Transmit Level (or transmit power) is a bulk measurement of the power of a
transmitted signal. This measurement is a factory calibrated and normalized
such that a 0 dB reading for 100BaseTx corresponds to a nominal, 2Vpp, 4
nsec Rise/Fall time transmitted signal and a 0 dB reading for 1000BaseT
corresponds to a nominal peak-to-peak voltage of 1.5V from Point A to Point B
on the gigabit Test Signal #1 (see Figure 1.11).
Transmit Level (also referred to as Tx Level) should be thought of as the
integrated power within the full signal spectra as compared with that of a
nominally powered signal. It bears an approximate relationship with the peak-
peak level of a transmitted signal, though as stated in Section 1.3.3, the peak-
peak voltage will relate more closely to lower frequency power (e.g. 2 MHz
PSD) than to the wide-band power measurement made with this meter.
The Tx Level measurement is used inside of PSD calibrations to assure a more
accurate zero dB baseline to PSD measurements. When evaluating Ethernet
ports, Transmit Level is a quick indication of total signal power relative to a
nominal 100BaseTx or 1000BaseT signal. It will respond dB-for-dB if a fixed,
flat frequency power loss (or pad) is placed in line with an Ethernet transmitter.
1.3.6. Pair Skew Measurement
The Pair Timing Skew measurement is only applicable in 1000BaseT links.
This meter very simply reports the timing differences between the 4 incoming
pairs (see Figure 1.12). Measurements are reported in nanoseconds and are
normalized to one of the four pairs meaning one pair will always read zero
nsec. Meter granularity is 8 nsec, or one symbol period.
The IEEE standard requires that delays between the four pairs should never
exceed 50 nsec. This equates to just over 6 symbol periods. This requirement
exists to assure receivers can properly reassemble data streams split amongst
the four pairs.
1.3.7. Interface Verification –Overview
The PhyView Analyzer will verify two types of interface characteristics while linked at 1000BaseT.
Bulk Return Loss (or Echo)
Bulk Pair-Pair Crosstalk
These characteristics are separated from Transmitter and Receiver testing since they are not strictly related to the PHY
transmitter or receiver. The measurements made required that the port-under-test support gigabit Ethernet. The
values obtained however are not likely related to link rate and are generally applicable at any of the link rates 10, 100,
or 1000BaseT. Of course, 10BaseT is much less sensitive to return loss or crosstalk because of it’s relative narrow
frequency band.
1.3.8. Bulk Return Loss (Echo) Measurements
Bulk Return Loss (or Echo Response) is a measure of the power ratio between transmitted power and incident
reflected power. Transmitted power is reflected whenever there are discontinuities or mismatches in the transmission
path of a signal. 10/100/1000BaseT interfaces are designed for 100transmission paths meaning that source and
termination impedances, as well as characteristic impedance, are nominally 100over the applicable frequency range.
The term “bulk” indicates that the measurement is not reported as a function of frequency. It is simply a wideband
bulk power ratio. It is available only in 1000BaseT because that technology was designed to enable signal power
measurements that are correlated only to a specific transmission direction on a specific pair. In other words, the Bulk
Return Loss measurement takes advantage of features that are unique to 1000BaseT.
100BaseTx: 0 dB
1000BaseT: 0 dB
Test Signal #1
2.000 Vpp
4.0 nsec
1.500 Vpp
A
B
Mask
100BaseTx: 0 dB
1000BaseT: 0 dB
Test Signal #1
2.000 Vpp
4.0 nsec
1.500 Vpp
A
B
Mask
Figure 1.11 Zero dB Transmit Level
-16 nsec -8 nsec 0nsec-16 nsec -8 nsec 0nsec
Figure 1.12 Pair Timing Skew

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The IEEE 802.3 specification for Return Loss was
written with the constraint that Category 5 cabling may
have a characteristic impedance between 85 and 115
(see Figure 1.13). Normally, a return loss measurement
would be specified assuming a single, fixed channel
impedance such as 50. However in 802.3, it is
essentially specified with two reference impedances,
85and 115. It is then expressed as a formula that
changes over frequency. The limit line formula from
802.3 clause 40.8.3.1 is:
Return Loss (<40MHz) < - 16 dB
Return Loss (>40MHz) < - (10–20*LOG(MHz / 80))
dB
To make this specification relevant to a test apparatus
that has fixed 100impedance, some transformations are necessary. The following table shows what the port-under-
test must look like to a 100source in order to meet the return loss requirements of -16dB (40MHz) and –8dB
(100MHz). It also computes a figure for –15.5 dB since, given the known 1000BaseT signal spectra (see Figure 1.6),
-15.5 dB approximately represents the wideband Echo power of a hypothetical port-under-test that tracks the 802.3
limit line function over frequencies from 1 to 100MHz.
Source
Impedance
Return Loss
Port Under Test
Impedance
Observation
85 
-16 dB
61.8 to 117 
83.5 to 117 will produce < -16 dB given a
reference anywhere between 85 and 115 
-8 dB
36.6 to 197 
-15.5 dB
60.6 to 119 
49.5 to 197 will produce < -8 dB given a
reference anywhere between 85 and 115 
115
-16 dB
83.5 to 158 
-8 dB
49.5 to 267 
82.1 to 119 will produce < -15.5 dB given a
reference anywhere between 85 and 115 
-15.5 dB
82.1 to 161
PVA
Impedance
Port Under Test
Impedance
Expected
Return Loss
Applicable Frequencies
100
Frequency
Selective
83.5
-20.9 dB
Frequency Range 0 –40 MHz
117
-22.1 dB
49.5
-9.4 dB
@ 100MHz
197
-9.7 dB
100
Wideband
82.1
-20.1 dB
Bulk Return Loss Limits that assure MDI Return
Loss specs across 85 to 115
119 
-21.2 dB
Using this table, the wideband criteria for a compliant interface would be in the –20 to –21 dB Return Loss region.
The Return Loss metrology is restricted to a floor of –26 dB and an error magnitude of 1 to 1.5 dB. So a fair criteria to
apply to a typical port-under-test would be in the –19 to –20 dB range.
Bulk Return Loss is a calibrated measurement so that effects of cabling, connectors, and even test receivers are
properly compensated. Fully automated calibrations that require no external calibration standards simplify the task of
periodic calibration. Bulk Return Loss can be readily used to measure return loss across link components including
cabling, connectors, and patch panels.
1.3.9. Bulk Pair-Pair Crosstalk
Crosstalk is a ratio between the power transmitted on a single cable pair and the portion of that transmitted power that
leaks across into other cable pairs. It is generally thought of as a property of multi-pair cabling and connector
components. Typically, crosstalk increases with frequency owing to capacitive coupling between components.
IEEE 802.3 does not explicitly specify crosstalk performance of a 100/1000BaseT PHY, however it does specify the
use of TIA/EIA 568 (ISO/IEC 11801) qualified connectors that are in turn subject to various crosstalk specifications.
IEEE 802.3 also specifies expected near-end crosstalk (see Figure 1.14) performance of physical links that connect
Ethernet ports with the formula:
NEXT < 27.1 –16.8*LOG( MHz / 100 ) dB
Figure 1.13 IEEE 802.3 Return Loss Specification

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Ethernet ports can contribute to crosstalk in several
ways. Defective components and circuit trace
layout issues may lead to excessive crosstalk either
as a design feature or on an occasional port basis.
Many Ethernet ports utilize magnetics packages
that combine all 4 pairs into a single compact
package with tight spacing between coils.
Mechanical defects in sockets may also add to
crosstalk.
The PhyView Analyzer offers a calibrated
Crosstalk measurement that assesses near-end
crosstalk at the port-under-test interface. The
measurement reports crosstalk by pair
combination, that is, crosstalk between Pair #1 and
Pair #2 or between Pair #2 and Pair #4. (See
section 1.3.10 for discussion of pair numbering
convention.)
There are six unique pair combinations (see Figure 1.14):
Pair 1 to 2
Pair 2 to 3
Pair 1 to 3
Pair 2 to 4
Pair 1 to 4
Pair 3 to 4
The PVA Crosstalk measurement assumes that all crosstalk is bi-directional, that is, that crosstalk is really a
measurement of electrical isolation between two pairs. Well isolated pairs will report low crosstalk and poorly isolated
pairs will report higher crosstalk.
Much like the Return Loss measurement, Crosstalk is a wideband or bulk measurement across all frequencies, can only
be performed while linked at 1000BaseT, and is reported in dB. It is available only in 1000BaseT because that
technology was designed to enable signal power measurements that are correlated only to a specific transmission
direction on a specific pair.
Since there are no explicit limits from IEEE 802.3, hypothetical performance limits need to be discerned from other
specifications. In a 10/100BaseT channel, the only crosstalk that matters is Pair 2-3 since pairs 1 and 4 are not utilized
for data communication. In 1000BaseT, all four pairs are utilized in a full duplex fashion and any crosstalk that can be
measured on any pair will create an uncorrectable distortion at the receiving end of the link. If the link between two
ports were ideal, then the full budget of the NEXT formula limit line (see above) could be applied to the port-under-
test. Crosstalk would then range from –60dB at 1 MHz up to –27dB at 100MHz.
Given the spectral characteristics of a 1000BaseT transmission, the wideband equivalent to the NEXT formula limit
line approximates –37.8 dB. That is, the allowable crosstalk between any two pairs is about 0.017% of transmitted
power. The Crosstalk metrology is restricted to a floor of –39 dB and an error magnitude of 1 to 1.5 dB. This means
that the Crosstalk measurement is particularly useful for exposing design or manufacturing defects that cause
performance to degrade by worse than 3 to 6 dB relative to what the 802.3 standard hypothetically allows.
1.3.10. Pair Designators in the PhyView Analyzer
The PhyView Analyzer adheres to a pair numbering convention used in TIA/EIA-568-B. This convention is
commonly recognized throughout the cabling and connector industry. In this convention, pair numbers are related to
colors and RJ-45 connector pin numbers as follows:
Pair
Number
Pair Colors
RJ-45
Pins
Description
1
Blue & Blue/White
4& 5
Spare Pair for 10/100BaseT
2
Orange & Orange/White
2& 1
MDI Transmit / MDI-X Receive Pair for 10/100BaseT
3
Green & Green/White
6& 3
MDI-X Transmit / MDI Receive Pair for 10/100BaseT
4
Brown & Brown/White
8& 7
Spare Pair for 10/100BaseT
Figure 1.14 PVA Crosstalk Measurement

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1.3.11. Receiver Verification Overview
Unlike transmitter testing, 10/100/1000BaseT receiver testing is
not generally addressed in 802.3 standards. 802.3 standards do
define the worst-case link (or cabling systems) environment for
Ethernet ports with specifications for channel insertion loss, return
loss, and crosstalk. These specifications are ultimately derived
from TIA/EIA 568 specifications related to Category 5/5e cabling
systems. Transmitted signal characteristics such as signal
amplitude range, clocking frequency, distortion parameters, and
timing jitter are also thoroughly specified in the standards and by
inference create additional constraints on required receiver
performance. Finally, allowances for added noise, or alien
crosstalk also affect receiver requirements. This collection of
receiver requirements is depicted in Figure 1.15.
The 10BaseT and 1000BaseT specifications also define explicit goals for bit error rate (BER) performance. The
100BaseTx specification, and its subsidiary TP-PMD specification make no mention of bit error rate targets. Section
1.2.5 above raised the additional issue that BER is not directly measurable and must be inferred from packet flow
measurements.
The table below summarizes specifications that are relevant to 10/100/1000BaseT receiver testing.
Link Rate
Target BER
Cabling System
Rx Noise Insertion
Target Packet Error Rate
1000BaseT
10-10
Cat5e
-24dB @100MHz
25mVp-p
100BaseTx Spectrum
10-7 (125 octet frames, no
account for coding ovhd.)
100BaseTx
Unspecified
(UNH: 10-8)
Cat5
-24dB @100MHz
40mVpp
Band Limited 100MHz
Unspecified
(UNH: 1.5*10-5, 64 octet
frames)
10BaseT
10-8
Cat3
-11.5dB @10MHz
300mVpp
Band Limited 15MHz
Unspecified
(5.12*10-6, 64 octet frames)
Summarizing, receiver test methodology is largely the responsibility of Ethernet port designers and implementers. The
task of modeling all of the possible signal and channel impairments while assessing bit error rate performance can be
daunting and the exact criteria for success (pass or fail) can be ambiguous.
1.3.12. Receiver Testing Metrology
The PhyView Analyzer offers two distinct measurement techniques for receiver testing:
1. Link Monitor: Receiver Measurements on stand-alone Ethernet ports
5. Packet Flow: Receiver Measurements on multi-port (bridging) devices such as switches, hubs, and repeaters
The Link Monitor was introduced in Section 1.3.1. This measurement resource assesses both instantaneous and time-
sampled Link Status, as well as other link configuration parameters. In receiver testing, the key parameter is sampled
Link Status. Link Status can be one of three physical layer indicators:
1. Link State, that is link UP (linked) or link DOWN (unlinked) –available for 10/100/1000BaseT
6. Remote Rx Status, a physical layer indicator from the link partner indicating Rx “OK” or Rx “Not OK” –
available for 1000BaseT only.
7. Local Rx Status, a physical layer indicator from the test port receiver indicating Rx “OK” or Rx “Not OK” –
available for 1000BaseT only.
Link Status can be a single, instantaneous sample or can be configured to report a count of up to “UP” or “OK”
samples evenly spaced with sampling intervals of 20, 50, or 100msec, whereupon it becomes a Link Stability
measurement.
Generally, the criteria for link “UP” in 10BaseT is the continuous receipt of link test pulses (see Figure 1.16). A
highly impaired 10BaseT receiver-under-test may or may not choose to continue transmission of link pulses meaning
there is no sure way for one link partner (or Test Port) to discern the receive condition of the other link partner. This
means that Link Stability generally will not correlate linearly to a hypothetical port-under-test bit error rate or packet
error rate.
Figure 1.15 Ethernet Port Rx Requirements

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When testing 100BaseTx receivers, the ability of the Link State to predict or estimate effective packet loss in a port-
under-test receiver is very much implementation dependent since the 100BaseTx standard is nebulous about the action
of receivers that are experiencing any degree of packet loss. Some PHY implementations may recognize error
conditions and attempt to force a re-link to overcome it. Any re-link can be detected as a link drop by the Link
Monitor.
In re-linking, some 100BaseTx PHY implementations may naturally drop back
to 10BaseT in an attempt to overcome serious channel impairments. The loss
thresholds at which any given PHY implementation makes decisions to drop
link and re-link is unspecified. Conversely, some PHY implementations, when
auto-negotiated to 100BaseT, will attempt to maintain 100BaseT link by
transmitting continuous IDLE MLT-3 signaling (see Figure 1.16) even when
incoming packet traffic and IDLE signaling is 100% impacted by bit errors.
Summarizing, for 100BaseTx, the relationship between Link Stability and
packet loss can range from very weak to very strong depending the PHY
implementation in the port-under-test.
1000BaseT introduced the concept of a receive status indicator combined with a
purely physical layer signaling protocol to communicate receiver status to the
link partner while linked (see Figure 1.16). Because of DSP processes
including forward error correction that are inherent in receiving 1000BaseT
signals, PHY implementations could more readily discern and communicate bit
error problems even when link performance was reasonably good. The Link
Monitor takes advantage of this feature in 1000BaseT by allowing Link State
(“UP” or “DOWN”) to be replaced by Remote Rx Status “OK” or “Not OK”.
Remote Rx Status can be sampled periodically from 1 to 100 samples at periodicity of 20, 50, or 100msec. Remote
Rx Status is a reasonably good predictor of bit error and packet loss performance.
The second option for receiver measurements in the PhyView analyzer is a simple Packet Flow measurement. This
involves the transmission of user-specified packets (size, gap, payload) into the port-under-test. The packets generated
by each PhyView Analyzer test port are restricted to MAC frames with programmable address, size, packet gap, and
repeating 4-byte payload. This technique therefore requires that the port-under-test must forward any successfully
received packets to another Ethernet port so that they may be returned to another PhyView Analyzer test port. Hence,
the device being tested must be a multi-port device with layer 2 bridging capability such as an Ethernet switch, hub, or
repeater.
The obvious advantage of packet flow testing is that it will always provide insight to the bit error performance of a
receiver regardless of link rate, that is 10BaseT, 100BaseTx, or 1000BaseT.
A disadvantage of Packet Flow is that it cannot be used on single-port devices or devices that don’t bridge layer 2
packet traffic. Another disadvantage is that it consumes two PhyView Analyzer test ports and is generally a bit more
complicated to configure and initialize than the Link Monitor. Often, layer 2 bridging must be “primed” in an Ethernet
switch as it executes spanning tree protocols in order to isolate connection paths. Finally, the PhyView Analyzer will
not filter received packets so that any rogue, unsolicited packets (e.g. LLDP or CDP) will add to received packet
counts, though usually at very low levels.
1.3.13. Receiver Testing with Impairments
A major contribution of the PhyView Analyzer toward 10/100/1000BaseT receiver testing is the ability to apply a
range of controlled and relevant impairments. Impairments are vital for moving the BER performance of any receiver-
under-test to a point where it can be measured much more quickly and can also be statistically compared to the BER
performance of other receivers.
Figure 1.17 diagrams this phenomenon and provides a quantitative perspective. For example, if the BER performance
of an unimpaired receiver is 10-11, that is one error in 1011 bits, testing at 100BaseTx would yield a test time of over 13
minutes to discover the first packet error even when testing with the maximum packet size of 1518 octets. In
1000BaseT, this time is reduced by a factor of 10 and becomes just under 1½ minutes. Following up on the
relationships between packet errors and bit error rate (see Section 1.2.5), statistically, it takes many packet errors to
assess BER.
Impairing the receiver-under-test will drive up the BER, increase packet drops and packet error, and assess that receiver
under typical and worst case stresses.
Figure 1.16 Link Status Monitor